Google play services not working

I'm trying to implement google play services in my game, but it doesn't seem to work. I've done everything as specified- Linked my app to play services in the developer console. Added the SHA1 from Applications -> Release Management -> App signing -> Upload certificate. Downloaded the latest 'play services' unity package from GitHub. Added the required 'resource' to the play services setup in unity editor. Added the following script:

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 using GooglePlayGames;
 using GooglePlayGames.BasicApi;
 using UnityEngine.SocialPlatforms;
 
 public class PlayGamesServices : MonoBehaviour
 {
     // Start is called before the first frame update
     void Start()
     {
         PlayGamesClientConfiguration clientConig = new PlayGamesClientConfiguration.Builder().Build();
         PlayGamesPlatform.InitializeInstance(clientConig);
         PlayGamesPlatform.Activate();
         Social.localUser.Authenticate((bool success) =>
         {
             if (success)
                 Debug.Log("Logged In");
             else
                 Debug.Log("Failed to Log In");
         });
     }
 
     public static void PostToLederboard(long newHighScore)
     {
         Social.ReportScore(newHighScore,GPGSIds.leaderboard_global_high_score,(bool success) =>
         {
             if (success)
                 Debug.Log("New High Score posted");
             else
                 Debug.Log("Unable to post New High Score");
         });
     }
 
     public void ShowLeaderboard()
     {
         PlayGamesPlatform.Instance.ShowLeaderboardUI(GPGSIds.leaderboard_global_high_score);
     }
 }

Built the APK and when i run on device, nothing happens. I've tried editing the proguard file from this link but the build failed with 67 errors. I don't know what I'm doing wrong or what I'm missing.